FR2473165A3 - ATOMIZING DRYER WITH ECONOMIZER DEVICE - Google Patents

Abstract

ATOMIZING DRYER WITH AN ECONOMISER DEVICE. THIS DRYER INCLUDING A HOMOGENEIZATION TANK3, A PUMP 5 AND ATOMIZATION MEANS OPERATING IN THE DRYING CHAMBER 9 IS CHARACTERIZED BY THE FACT THAT THE DRYING AIR OUTLET OF CHAMBER 9 IS CONNECTED WITH A DUCT 13 LEADING TO A PRE-DRYING CHAMBER 2 WHICH HAS A FIRST AIR EXHAUST OUTLET 14, AND INSIDE WHICH IS PROVIDED AT LEAST ONE SPRAYER 7, WHICH PUMP 5 AND PULVERISER 7 ARE PROVIDED HEATING MEANS, THAT CHAMBER 2 SHOWS A SECOND OUTPUT CONNECTED TO A SECOND INPUT OF TANK 3 AND THAT THE HEATING MEANS BRING THE LIQUID TO THE TEMPERATURE BETWEEN THE BOILING TEMPERATURES AT THE PRESSURE OF CHAMBER 2 AND THE PRESSURE POWER SUPPLY.

Description

1 22473165

  The object of the present invention relates to a spray dryer having a device for reducing, per unit weight of dried product, the amount of heat necessary to evaporate the liquid that maintains in solution or suspension in the conduits that lead to the nebulizing or atomizing device. Spray dryers are known in which the solution or suspension (generally aqueous) intended to be dried is nebulized in a drying chamber into which hot air is also introduced which causes the rapid heating of this same solution or suspension finely pulverized. and consequently the evaporation of the suspension or solution liquid to the desired percentage, at the same time obtaining

  granulation of the dried product in the desired particle size.

  It is also known that suspensions, obtained for example by wet grinding of raw materials, often contain more solvent than is strictly necessary to allow nebulization to the desired particle size. However,

  this excess solvent can not be separated in a satisfactory manner.

  doing so by mechanical means, so that until now it is also separated in the drying chamber, which has for

  consequence of limiting its yield and increasing the

  heat per unit of dried product.

  The main object of the present invention is that of eliminating these disadvantages by producing an atomization dryer in which the suspension or solution which reaches the final drying chamber of the product has a minimum content of solvent necessary for the nebulization, so as to what the solvent

  in excess can be eliminated with the least specific consumption.

possible.

  Another object of the present invention is to achieve the foregoing purpose with a simple, relatively easy-to-implement structure that is safe for use and efficient operation.

  while being of relatively limited cost.

  These goals, as well as others that will become more apparent later, are all achieved by the present economizer atomizer dryer including a

  homogenisation tank of the product to be dried, a feed pump

  product and means of nebulization or atomization

2 2473165

  of the product connected in series with one another, said nebulizing means operating inside a drying chamber, characterized in that at the outlet of the drying air of said chamber is connected a conduit which leads to a pre-drying chamber which has a first exit exhaust air exhausted to the outside, and within which is provided at least one sprayer powered by said pump, that between the pump and said sprayer are arranged heating means, said pre-drying chamber has a second outlet of the pre-dried product connected to a second inlet of said tank, and said heating means are able to carry said suspension or solution to a temperature higher than that of boiling at the pressure of the pre-drying chamber, but lower than the boiling temperature at the feed pressure, the liquid passing, passing through said spray feed pressure to that of the pre-drying chamber and self-evaporating in a

  large proportion with reduced heat consumption.

  Other features will emerge more clearly

  of the following detailed description of an embodiment

  preferred but not exclusive of a dryer according to the invention, given here by way of non-limiting example, with reference to the appended drawing, in which: - the single figure represents a block diagram of a

dryer according to the invention.

  According to said figure, the reference 1 indicates the dryer according to the invention, while the reference 2 indicates

said pre-drying chamber.

  The aqueous suspension reaches tank 3 from previous storage tanks, and is directed through line 4 to a pump 5 which, through line 4a,

  introduced into the exchanger 6 which is a heating means.

  Then, after being warmed to a higher temperature

  to that of boiling water at the pressure of the chamber of pre-

  drying, said suspension is sent by the pump, through the

  duct 4b, to the sprayer 7.

  Inside the sprayer the aqueous suspension

  goes from the supply pressure to that of the chamber of pre-

  drying undergoing a substantially adiabatic transformation.

  During this transformation, the suspension, given its temperature,

  at the sprayer inlet, gives off steam without any

3 2473165

  need to receive heat from the surrounding environment and therefore without other heat losses with exhausted air. After being thus partially dehumidified, the aqueous suspension returns through the conduit 8 to the homogenization tank 3, from which it is taken up by the pump through the conduit 4 and then sent through the conduit 4c to the system atomization present in the drying chamber 9, from which the dried product finally exit the outlet 10. The drying air, taken at 11, is heated in the hot air generator 12 and then sent through the duct 11 to the drying chamber 9 where it will exit through 13, cooled and enriched with moisture, to reach the pre-drying chamber 2. In this chamber 2 the air is brought to saturation and then sent, through the conduit 14, towards the chimney

  extraction or to a purification plant.

  It is easy to realize that at equal evaporation capacity the drying chamber 9 will produce a larger quantity of dried product, since the moisture of the suspension sucked at 4 will be substantially less than that from the tanks.

  previous through the conduit 16.

  The temperature at which the aqueous suspension is brought is quite low, the heat supplied to it in the exchanger 6 may advantageously be heat recovery from eg the cooling circuit

  and exhaust of thermal mortgers.

  It can be seen, therefore, that the invention reaches

  the aims envisaged and in particular that it makes it possible to obtain

  significant savings in energy and construction.

  Of course, the invention thus conceived is susceptible of numerous modifications and variants all falling within the

framework of the same inventive concept.

  Likewise, all the elements of detail can be

  replaced by other technically equivalent elements.

  Finally, in practice, the dimensions and shapes, as well as the materials used, may be any depending on the requirements, without departing from the scope of the

  protection of the claims that will follow.

4 2473165

Claims (1)

CLAIM   1. Dryer (1) with atomization device with economizer, comprising a reservoir (3) for homogenizing the product to be dried, a pump (5) for supplying the product and means for atomizing the product connected in series with one another. to the other, the said atomic means   operating within a drying chamber (9), which is   characterized in that at the outlet of the drying air of said chamber is connected a conduit (13) leading to a pre-drying chamber (2) which has a first outlet (14) for evacuation of the air exhausted to the outside, and inside which is provided at least one sprayer (7) supplied by said pump (5), that between the pump (5) and the sprayer (7) are arranged means of heating, said pre-drying chamber (2) has a second outlet of the pre-dried product connected to a second inlet of said tank (3), and said heating means are able to bring said suspension or solution to a temperature higher than that boiling under pressure of the pre-drying chamber (2), but below the boiling temperature at the feed pressure, the liquid passing, through said sprayer, from the supply pressure to that of the pre-drying chamber (2) and self-evaporating in   a significant proportion with reduced heat consumption.